Williams's victory puts her in the fourth round for the second straight year. She hadn't made consecutive fourth rounds since 2007-10.

Williams made the quarterfinal last year before losing to sister Serena. This year, she'll face No. 10 seed Karolina Pliskova in the fourth round. We're just two wins away from each of the Williams sisters from a Serena–Venus semifinal...but I think I'm getting ahead of myself.

No. 3 Stan Wawrinka d. Daniel Evans: What a match. Daniel Evans played wonderful tennis, and forced a match point in the fourth set. But Wawrinka somehow escaped from Louis Armstrong with a 4-6, 6-3, 6-7(6), 7-6(8), 6-2 victory. It wasn't always pretty—Wawrinka's signature backhand wasn't its best on Saturday, which is also credit to Evans—but Wawrinka found a way to get it done, saving a match point during the fourth–set tiebreaker and rallying to win.

"It's always good to win by saving match point. It's always something special, that's for sure," Wawrinka said. "It was a great atmosphere again today on that court."

Wawrinka's next opponent? It was almost Nick Kyrgios—but instead he'll play Illya Marchenko, with whom he has just a bit less personal history.

Illya Marchenko d. No. 14 Nick Kyrgios: Wawrinka–Kyrgios will have to wait for another time. Kyrgios exited the tournament after he was forced to retire after three sets against Illya Marchenko. After Kyrgios won the first set, Marchenko won a tight second set before cruising in the third against a clearly hobbled Kyrgios.

Kyrgios, who had acknowledged a hip issue earlier in the tournament, said after the match that he has to do a better job preparing physically to avoid situations like Saturday night.

"I got to take more time and be more diligent with gym and everything so this doesn't happen to me," he said.

Kyrgios was in tears at times on Saturday night, and it's hard not to feel for him. But also give credit to Marchenko, who reached the round of 16 at a Slam for the first time in his career. Pretty awesome moment.

No. 21 Ivo Karlovic d Jared Donaldson: Donaldson's surprise run to the third round came to an end on Court 17, as Ivo Karlovic beat the 19-year-old American qualifier 6-4, 7-6(3), 6-3. Playing in his third Grand Slam event—all U.S. Opens—Donaldson made it out of the first round for the first time, and beat two quality players in David Goffin and Viktor Troicki. It remains to be seen whether this tournament marks a turning point in his young career, but he can walk away feeling great about his effort this week.

Karlovic has had an excellent summer, winning a title in Newport before falling just short in Washington, D.C.​ This tournament, Karlovic has played the role of American slayer: In the second round, he beat Donald Young on Court 17, and he followed that up by beating Donaldson on the same court.

The 6'11" Croatian, who is 37, is into the fourth round of the U.S. Open for the first time in his career. He'll face Kei Nishikori in the next round.

No. 6 Kei Nishikori d. Nicolas Mahut: Nishikori quietly advanced to the fourth round of the U.S. Open for the third time in his career with a 4-6, 6-1, 6-2, 6-2 over Nicolas Mahut. The last time Nishikori advanced to the fourth round, of course, he ended up making the final. Nishikori is still a long way off from a repeat of his 2014 effort, but he has a favorable draw in the fourth round, where he'll meet either Ivo Karlovic. Time to start paying attention to Kei Nishikori.